Re: gcc fixed size char array initialization bug - known?

[Robert Hancock <hancockr@shaw.ca>]

Guennadi Liakhovetski wrote:
> On Thu, 2 Aug 2007, Andi Kleen wrote:
>
> > Guennadi Liakhovetski <g.liakhovetski@gmx.de> writes:
> >
> > > 	char c[4] = "0123";
> > > and - a wonder - no warning. 
> > It's required by the C standard.
> >
> > 6.7.8.14 of C99:
> > ``
> > An array of character type may be initialized by a character string literal, optionally
> > enclosed in braces. Successive characters of the character string literal (including the
> > terminating null character if there is room or if the array is of unknown size) initialize the
> > elements of the array.
> > ''
> >
> > Note the "if there is room".
> >
> > I believe the rationale is that it still allows to conveniently initialize 
> > non zero terminated strings.
>
> Right, I accept that it will compile, but I don't understand why "01234" 
> produces a warning and "0123" doesn't? Don't think C99 says anything about 

Because 5 characters will not fit in a 4 character array, even without 
the null terminator.

> that. And, AFAIU, using structs with fixed-size char array we more or less 
> rely on the compiler warning us if anyone initializes it with too long a 
> string.
>
> Also interesting, that with
>
> 	char c[4] = "012345";
>
> the compiler warns, but actually allocates a 6-byte long array...
>
> Thanks
> Guennadi


--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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